A wide variety of light emitting devices are known in the art including, for example, incandescent light bulbs, fluorescent lights, and semiconductor light emitting devices such as light emitting diodes (“LEDs”).
White light may be produced by utilizing one or more luminescent materials such as phosphors to convert some of the light emitted by one or more LEDs to light of one or more other colors. The combination of the light emitted by the LEDs that is not converted by the luminescent material(s) and the light of other colors that are emitted by the luminescent material(s) may produce a white or near-white light. White lighting from the aggregate emissions from multiple LED light sources, such as combinations of red, green, and blue LEDs, typically provide poor color rendering for general illumination applications due to the gaps in the spectral power distribution in regions remote from the peak wavelengths of the LEDs. Significant challenges remain in providing LED lamps that can provide white light across a range of CCT values while simultaneously achieving high efficiencies, high luminous flux, good color rendering, and acceptable color stability.
The luminescent materials such as phosphors, to be effective at absorbing light, must be in the path of the emitted light. Phosphors placed at the chip level will be in the path of substantially all of the emitted light, however they also are exposed to more heat than a remotely placed phosphor. Because phosphors are subject to thermal degradation, by separating the phosphor and the chip thermal degradation can be reduced. Separating the phosphor from the LED has been accomplished via the placement of the LED at one end of a reflective chamber and the placement of the phosphor at the other end. Traditional LED reflector combinations are very specific on distances and ratio of angle to LED and distance to remote phosphor or they will suffer from hot spots, thermal degradation, and uneven illumination. It is therefore a desideratum to provide an LED and reflector with remote photoluminescence materials that do not suffer from these drawbacks.